\subsection{Problem 5} Find $\mathbf{A^{-1}}$ to: \begin{equation*} \matr{A} = \begin{bmatrix} 2 & 1 & 2 \\ 1 & 2 & 3 \\ 4 & 1 & 2 \end{bmatrix} \end{equation*} solving the system $\mathbf{AX=I_{3}}$. \subsubsection*{Solution} \lstinputlisting[style=Matlab-editor]{problems/Problem5.m} which judges well our algorithms.